Methods for pleating or otherwise shaping a web can be used for a variety of purposes. Pleated webs can, for example, be useful in the construction of diapers and other absorbent articles, filters, window shades, and other articles. Methods of pleating webs are described in: U.S. Pat. No. 2,655,978, Gonda, et al.; U.S. Pat. No. 3,066,932, Greiner, et al; U.S. Pat. No. 3,165,310, Peterson; U.S. Pat. No. 3,401,927, Frick, et al.; U.S. Pat. No. 3,784,186, Lenthall, et al.; U.S. Pat. No. 5,589,014, Hicks; U.S. Pat. No. 4,170,347, Lewis; U.S. Pat. No. 7,235,115, Duffy, et al.; U.S. Pat. No. 7,963,899 B2, Papsdorf, et al.; EP 0364084 A1; Indian Patent Publication 189471; and UK Patent 1 433 910. In addition, a company by the name of Former Fab makes a device for corrugating a web. The webs that can be formed by its equipment are found on the website www.former-fab.de/en/ideas-innovations/longitudinal-corrugating-technology.
Applicants have found the need for an improved process for shaping a web in an area in which webs are typically more randomly shaped—in vertical forming, filling and sealing (VFFS) processes for making packages for unit doses of liquid products. Unit doses of liquid products such as shampoo and hair conditioner are often placed in relatively thin, flat packages known as sachets. Such sachets are typically provided with water vapor barrier properties to prevent water loss from the product in the package over time. Sachets of this type are generally made using vertical forming, filling and sealing (VFFS) processes.
Current processes exist for vertical forming, filling and sealing, both intermittently and continuously. Vertical forming, filling and sealing (VFFS) processes typically employ fill nozzles that are inserted in between two layers of material used to form the package. Current VFFS machines may have up to twelve nozzles lined up in a row across the width of the two webs of material in order to form and fill twelve sachets at the same time. These processes rely on the webs of material being forced together between the nozzles and held apart by the nozzles in order to create a space into which the product is dispensed by the nozzles. When the webs are forced together between nozzles, longitudinal seals are formed between the webs to close the sides of the sachets, and transverse seals are formed between each dose dispensed by the nozzles.
One problem with existing VFFS systems is that reliance upon the webs of material forming a space to dispense product as they pass around the nozzles is not precise, and can result in uneven widths of material forming different sides of the sachets. Thus, the material from one of the webs that forms the front of the sachet may have a different width than the material from the other web of material that forms the back of the sachet. This can lead to wrinkling of the sachets. Further, the wrinkling of webs can interfere with the formation of the transverse seals, so that the materials are not completely sealed together, leading to leaky sachets.
The search for improved methods and apparatuses for pleating or otherwise shaping a web, as well as improved package forming processes has, therefore, continued.